Preparation of amino pyrazolones



Patented May 22, 194,5

UNITED STATES PATENT orncs PREPARATION OF AMINO PYBAZOLONES Henry 1). Porter and Arnold Weissberger, Rochester, N. Y., asslgnors to Eastman Kodak Company, RochestenN. Y., .a corporation of New Jersey No Drawing. Application November 5, 194 2,

1 Serial No. 464,650

I Claims. (Cl. 260-305) This invention relates to the preparation of amino pyrazolones.

The preparation of 1-phenyl-3-hydroxy-5-pyrazolone imide is described by Conrad is Zart in Berlchte, vol. 39 (1906), page 2287. The reaction involves the use of phenyl hydrazine and ethyl cyanoacetate in the presence of sodium ethylate. These intermediates are heated for 20 hours at 120-130 -C. according t3 the Conrad .8; Zart method.

We have found that the Conrad 81 Zart method does not give 1-phenyl-3-hydroxy-6-pyrazolone imide, but produces 1-phenyl-3-amino-5-D71'azolone (J. Am. Chem. Soc., vol. 64, page 2133 (1942)). This compound, and its derivatives, are

valuable couplers for use in the color-forming process of color photography.

It is frequently desirable to prepare amino pyrazolones from hydrazines bearing substituents which will not withstand the long and drastic heat treatment demanded by the Conrad & Zart method, for example, p-nitrophenylhydrazine.

Amino pyrazolones formed from p-nitrophenyh,

hydrazine are valuable couplers for color photography and the lack of suitability of the Conradlz Zart method for their preparation necessitated a search for other methods.

It is, therefore, an object of the present invention to provide a new method for the preparation of aminopyrazolones. A further object is to provide a less drastic treatment of aryl, hy-.

drazines than that of Conrad & Zart in the preparation of amino pyrazolones. Other objects will appear frm..the rollowing description of our invention.

These objects are accomplished by condensing the appropriate phenyl hydrazine with ethyl (pethoxy-B-imlnmpropionate. v

The compounds which we produce with our new method are not all new, but the novelty resides in the provision of an easy method for preparing them. These compounds'have the following probable formula:

where R=ary l, alkyl, or a heterocyclicgroup. with heterocyclic hydrazlne's, e. g., z-benzo min hydrazine, 2-pyridyl hydrazine and 2- quinolyl hydrazine and cyanacetic eater, the 3- hydroxy-5-pyrazolone imides are obtained while the new method gives the 3-amino-5 -pyrazo- Ethyl (p-ethoxy-p-imlno)propionate is described in the literature as the imino. ethyl ether of ethyl cyanoacetate (Berichte, vol. 28, page 478, 1895). Our new synthesis is carried out by merely heating the two reactants on the steam both with or without a solvent.

Our method may be used with hydrazine itself, aryl hydrazlnes such as phenyl hydrazine, tolyl hydrazine, phenoxyphenyl hydrazine, nitrophenyl hydrazine, naphthyl hydrazine, and others, as well as with alkyl hydrazines, such as methyl and ethyl hydrazine, and heterocyclicsubstituted hydrazines.

Our invention will now be described by reference to the following specific examples:

Example 1 N=GNH: I-phenyI S-amInoJ-pyrazoIoneQN A mixture of 10 grams (.063 mole) of ethyl (pethoxy-p-imino) propionate and 6.8 grams (.063 mole) of phenyl hydrazine was heated on the steam bath for three hours. The resulting mush was slurried with 20 cc. of methyl alcohol, cooled and filtered. The yield was 5.5 grams '(50%),

M. P. 215-216 C.

' Example 2 v N=C-N Hs l-p-nitrophenyl-3-amino-5-pyrazoloneN0| ON A mixture of so-grams (.315 mole) of ethyl (nethoxy-p-imino) propionate and 48 grams (.315

mole) of p-nitrophenylhydrazine was heated together in 50 cc. of pyridine on .the steam bath for two hours. Then 50 cc. of methyl alcohol was added and the mixture cooled, 'flltered, and washed with methyl alcohol. The yield was 25 rams (36%) M. P. 248-2501 0.

Example 3 1 (2'-benzothiazolyl) -3-amino-5-pyrazoione (a) Ethyl-p[p'(2 benzothiazolyl)hydrazine]- p-imino-propionate.

A mixture of 15.9 grams (0.1 mole) of the imino ethyl ether of ethyl cyanoacetate and 16.5 grams (0.1 mole) of 2-benzothiazolylhydrazine in 75 cc.

of pyridine was heated on the steam bath for one hour. About 50 cc. of ethyl alcohol was then added and the precipitate filtered oif. Further precipitation occurred on adding water to the flitrate. A yield of 21.3 grams (76%) was obtained, M. P. 179-181" C.

(b) A solution of sodium ethylate was prepared from 4.6 grams (0.2 mole) of sodium and 100 cc. of ethyl alcohol. To this was added 27.8 grams (0.1 mole) of ethyl-p [p'(2-benzothiazoly1) hydrazinoJ-p-iminopropionate. This mixture was refluxed for one hour after which water was added to form a clear solution. Upon making acid, a heavy precipitate formed. A yield of 22.3 grams (96%) was obtained, M. P. 252-4 C.

The compounds produced by our method may be acylated in the usual way to produce acyl derivatives useful in color photography. Treatment of the aryl amino pyrazolone with acetyl chloride or benzoyl chloride produces a. monoacetyl or monobenzoyl derivative soluble in alkali which functions as a coupler.

We claim:

1. The method of producing a pyrazolone derivative, which comprises condensing a hydrazine selected from the class consisting of alkyl hydrazines, aryl hydrazines, and heterocyclic hydrazines, with ethyl (p-ethoxy-p-imino)propionate.

2. The method of producing a pyrazolone derivative of the following probable composition:

N=c-NH,

asraaeo where R is selected from the class consisting of alkyl groups, aryl groups, and heterocyclic groups, which comprises condensing a hydrazine selected from the class consisting of alkyl hydrazines, aryi hydrazines, and heterocycllc hydrazines, with ethyKp-ethOXy-p-iminQ) propionate.

' 3. The method of producing a pyrazolone derivative of the following probable composition:

where R is an aryl group, which comprises condensing an aryl hydrazine with ethylQB-ethoxyfl-imino) propionate.

4. The method of producing a 1-aryl-3-aminofi-pyrazolone, which comprises condensing an aryl hydrazine with ethyKp-ethoxy-g-imino)propionate by heating the reactants on a steam bath for two to three hours, and separating the resulting product.

5. The method of producing 1 --pheny1- 3 amino-5-pyrazolone, which comprises condenss phenyl hydrazine with ethyKp-ethOXy-p-imino)propionate by heating the reactantson a steam bath for two to three hours, and separating the resulting product.

6. The method of producing l-p-nitrophenyl- 3-amino-5-pyrazolone which comprises condensing p-nitrophenyl hydrazine with ethyl (fl-ethoxy- ,e-imino) propionate by heating the reactants on a steam bath for two or three hours, and separat ing the resulting product.

7. The method of producing 1(2'-benzothiazolyl) 3 amino-5-pyrazolone which comprises condensing 2-benzothiazolyl hydrazine with ethy1(p-ethoxy-p-imino)propionate by heating the reactants on a steam bath for about one hour in the presence of pyridine, separating the product, refluxing it with sodium ethylate, acidifying the solution, and separating the resulting product.

- HENRY D. PORTER.

ARNOLD WEISSBERGER. 

